Electric heater



Feb. 3, 1942. skGlLLlNG 2,271,973

ELECTRIC HEATER Filed July 10, 1939 v Inventor: Reginald S. Giflirg,

His Attorney.

- the usual practice, I form in the shape of a V with the apex of the V flattened for a short portion of its length, as shown.

The limbs of the V are arranged at about 120 i Patented Feb. 3, 1942 UNITED STATES PATENT OFFICE ELECTRIC HEATER Reginald S. Gilling, Rugby,

General Electric Company,

New York England, assignorto a corporation of 3 Claims.

This invention relates to electric heaters, more particularly to electric heaters of the hot plate type having one or more lengths of a sheathed wire resistance conductor arranged in one or more substantially flat coils, such as an 5 electric range heating. unit, and it has for-its object the provision of an improved electric heater of this character.

In one example of a heater of this type, the

hot plate. has two substantially concentric heating coils, and they are held in their relative positions by means of two strips of metal secured to each other substantially at right angles and provided with a number of indentations in which the turns of the coils are rigidly held. I

As-there is a very considerable expansion in the coils of the' heating elements when raised to their operating temperatures the above means of holding the turns in their relative positionscauses considerable distortion -of the elements and strains in the fixing strips and may result in buckling of the elements so that they are no longer fiat, or whereby the outer ends of the holding strips may get broken oil? leaving the outer turns of the elements loose.

This invention contemplates an improved electric heater wherein the holding strips for the various convolutions of the heating elements, instead of being rigidly fixed to each other, are relatively movable one to the other, thereby relieving the strains in the strips and heating elements during expansion and contraction of the elements.

For a more complete understanding of this invention, reference should be had to the accompanying drawing in which Fig. 1 is a plan view of an electric hot plate having two heating units arranged substantially concentrically and provided with holding means arranged.- in accordance with this invention;

Referring to the drawing, this invention has been shown in one form as applied to an electric hot plate provided with two holding; strips II and I! of metal having indentations the turns of the sheathed heating elements H and li'are secured. Instead of securing these holding strips together, as has hitherto been the strip ll roughly to each other and the second strip I2, which is preferably straight and is shorter than the first is provided with a reduced end portion it which and Fig. 2*is a 40 sectional view taken on the line 2-2 of Fig.1.

l3 in which slides easily in a recess or aperture l'l formed in the flattened portion'between the two limbs \of the V shaped strip II. The shorter strip I2 is also provided with indentations IS in which the coils of the heating elements are secured, and is arranged so that it makes an angle of nllaout 120 with the limbs of the V shaped strip The strips II and II, as shown, rest upon the bottom or a pin-like support l8 having an upright marginal side wall IS. The upper edge of this wall liesbelowjhe upper surfaces of the heating elements ll aiid l5 so as to leave them iree directly to support a cooking vessel.

With such an arrangement for holding the turns of the heater elements in their relative positions I nnd that the strains set up during expansion and contraction of the elements are greatly reduced and that permanent distortion of the heating elements or breakage of the supporting strips is substantially eliminated.

The heating elements I4 and I5 preferably will be of the type described in the United States v patent to C. C. Abbott No. 1,367,341, dated Feb- 25 .ruary 1, 1921. Briefly, this heater comprises 'a casing 20 housing a helical resistance element 2|. The element 2| is embedded in a comp cted mass of insulating material 22, such as powd red magnesium oxide.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric heating unit comprising a I.

sheathed wire resistance conductor formed into a substantially flat coil, metal supporting strips, means rigidly securing said strips to the convolutions of the coils, one of said strips, being substantially V-shaped with its limbs arranged at about 120? to each otherand its apex flattened, and theother strip being straight and having a tongue on one end which passes through a slot or groove provided for it in the flattened portion of the first mentioned strip;

2. An electric heatirig unit fo'ra range and the like comprising a pan-like support, a metalli- A cally sheathed heating element arranged in a substantially flat coil in said support, three intersecting supporting strips resting in radial positions on the bottom wall of said support, .means rigidly securing said strips to said cbnvolutions, a tongue and slot connection between one of said strips and the other two at their points of intersection to provide for free sliding movement between said one strip. and said other two so as to permit said convolutions to expand and contract.

3. An electric hot plate comprising a sheathed heating element formed into a convolution having its terminals on one side of the hot plate, a grid supportingsaid heating element comprising a pair of legs rigidly secured together and diverging from each other at their point of attachmentso as to span said terminals and another leg on the opposite side of said hot plate from said terminals meeting said pair of legs at their point of attachment, means providing, for free sliding relative movement between said third leg and said pair of legs at the point where said legs Join, and means rigidly securing said heating element to said legs, said free sliding movement providing for expansion and contraction of the portions of the turns of the heating elements opposite said terminals.

REGINALD S. GILLING. 

